- Ruxolitinib was recently approved for the treatment of patients with polycythemia vera who are resistant/intolerant to hydroxyurea based on data from the RESPONSE studies. This phase 3b, Expanded Treatment Protocol study (NCT02292446) of ruxolitinib for hydroxyurea-resistant/intolerant patients with polycythemia vera (N = 161: median exposure = 25.1 weeks) further evaluated the safety of ruxolitinib. Adverse events (AEs) led to dose adjustment/interruption in 37.9% of patients and study drug discontinuation in 8.7% of patients. The most common hematologic AEs included anemia and thrombocytosis; while headache and diarrhea were the most frequent nonhematologic AEs. At week 24, 45.3% of patients achieved hematocrit control; hematologic remission was seen in 18% of patients. At least, 50% of reduction in spleen length was achieved in 86.7% of patients from baseline at any time. The observed safety profile of ruxolitinib was consistent and the efficacy results were similar to the observed values in the RESPONSE studies.